German car manufacturer Volkswagen AG announced today that Jonathan Browning, who runs its U.S. division, would be stepping down. The change comes as the company is struggling with sluggish sales and continued turmoil at its Chattanooga, Tenn., plant over whether it will unionize.

Company executives want to expand production at Chattanooga but that has faced several snags. The only way to do it may be to allow the workers to unionize. Under German law, labor unions are given seats on company supervisory boards along with executives. These boards have veto power over major decisions and Volkwagen’s German union, IG Metall, is using its clout to oppose expansion in Chattanooga unless the workers there get representation.